Laser devices having a gallium and nitrogen containing semipolar surface orientation

ABSTRACT

Laser devices formed on a semipolar surface region of a gallium and nitrogen containing material are disclosed. The laser devices have a laser stripe configured to emit a laser beam having a cross-polarized emission state.

This application is a continuation of U.S. application Ser. No.13/794,410 filed Mar. 11, 2013 which claims the benefit under 35 U.S.C.§119(e) of U.S. Provisional Application No. 61/684,050 filed on Aug. 16,2012, both of which are incorporated herein by reference in theirentirety for all purposes.

BACKGROUND

In 1960, the laser was first demonstrated by Theodore H. Maiman atHughes Research Laboratories in Malibu. This laser utilized asolid-state flashlamp-pumped synthetic ruby crystal to produce red laserlight at 694 nm. By 1964, blue and green laser output was demonstratedby William Bridges at Hughes Aircraft utilizing a gas laser designcalled an Argon ion laser. The Ar-ion laser utilized a noble gas as theactive medium and produce laser light output in the UV, blue, and greenwavelengths including 351 nm, 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm,488.0 nm, 496.5 nm, 501.7 nm, 514.5 nm, and 528.7 nm. The Ar-ion laserhad the benefit of producing highly directional and focusable light witha narrow spectral output, but the wall plug efficiency was <0.1%, andthe size, weight, and cost of the lasers were undesirable as well.

As laser technology evolved, more efficient lamp pumped solid statelaser designs were developed for the red and infrared wavelengths, butthese technologies remained a challenge for blue and green and bluelasers. As a result, lamp pumped solid state lasers were developed inthe infrared, and the output wavelength was converted to the visibleusing specialty crystals with nonlinear optical properties. A green lamppumped solid state laser had 3 stages: electricity powers lamp, lampexcites gain crystal which lases at 1064 nm, 1064 nm goes into frequencyconversion crystal which converts to visible 532 nm. The resulting greenand blue lasers were called “lamped pumped solid state lasers withsecond harmonic generation” (LPSS with SHG) had wall plug efficiency of˜1%, and were more efficient than Ar-ion gas lasers, but were still tooinefficient, large, expensive, fragile for broad deployment outside ofspecialty scientific and medical applications. Additionally, the gaincrystal used in the solid state lasers typically had energy storageproperties which made the lasers difficult to modulate at high speedswhich limited its broader deployment.

To improve the efficiency of these visible lasers, high power diode (orsemiconductor) lasers were utilized. These “diode pumped solid statelasers with SHG” (DPSS with SHG) had 3 stages: electricity powers 808 nmdiode laser, 808 nm excites gain crystal which lases at 1064 nm, 1064 nmgoes into frequency conversion crystal which converts to visible 532 nm.The DPSS laser technology extended the life and improved the wall plugefficiency of the LPSS lasers to 5-10%, and further commercializationensue into more high end specialty industrial, medical, and scientificapplications. However, the change to diode pumping increased the systemcost and required precise temperature controls, leaving the laser withsubstantial size, power consumption while not addressing the energystorage properties which made the lasers difficult to modulate at highspeeds.

As high power laser diodes evolved and new specialty SHG crystals weredeveloped, it became possible to directly convert the output of theinfrared diode laser to produce blue and green laser light output. These“directly doubled diode lasers” or SHG diode lasers had 2 stages:electricity powers 1064 nm semiconductor laser, 1064 nm goes intofrequency conversion crystal, which converts to visible 532 nm greenlight. These lasers designs are meant to improve the efficiency, costand size compared to DPSS-SHG lasers, but the specialty diodes andcrystals required make this challenging today. Additionally, while thediode-SHG lasers have the benefit of being directly modulate-able, theysuffer from severe sensitivity to temperature, which limits theirapplication.

SUMMARY

The present invention relates generally to optical techniques. Morespecifically, the present invention provides methods and devices usingsemipolar oriented gallium and nitrogen containing substrates foroptical applications.

In an example, the present invention provides a laser device. The deviceincludes a gallium and nitrogen containing material having a semipolarsurface configured on one of either a (60-6-1), (60-61), (50-5-1),(50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21),a (30-3-2), a (30-32), and/or an offcut orientation. A laser striperegion is formed overlying a portion of the semipolar surface. The laserstripe region is characterized by a cavity orientation substantiallyparallel to the projection of the c-direction. The laser stripe regionhas a first end and a second end. A first facet is provided on the firstend of the laser stripe region and a second facet is provided on thesecond end of the laser stripe region. The device has an n-type claddingregion overlying the semipolar surface. The device has an active regioncomprising at least one active layer region overlying the n-typecladding region. The at least one active region comprises a quantum wellregion or a double hetero-structure region. A p-type cladding region isoverlying the active region. The laser stripe region is characterized bya width configured to emit a laser beam having a selected polarizationratio of a first polarization state and a second polarization state. Thepolarization ratio between the power emitted in the first polarizationstate and the power emitted in the second polarization state is greaterthan 0.9 or the ratio is at least 0.10 and the first polarization stateis orthogonal to the second polarization state. In certain embodiments,the emitted laser radiation is linearly polarized, in certainembodiments, circularly polarized, and in certain embodiments, theemitted laser radiation is elliptically polarized. As will be describedbelow, the polarization of the emitted radiation is determined by thebirefringent properties of the laser stripe waveguide.

In an example, the present invention provides a laser device. The deviceincludes a gallium and nitrogen containing material having a semipolarsurface configured on one of either a (60-6-1), (60-61), (50-5-1),(50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21),a (30-3-2), a (30-32), and/or an offcut orientation. A laser striperegion is formed overlying a portion of the semipolar surface. The laserstripe region is characterized by a cavity orientation substantiallyparallel to the projection of the c-direction with a length ranging from20 μm to 500 μm and a width ranging from 1 μm to 50 μm. The laser striperegion has a first end and a second end. A first facet is provided onthe first end of the laser stripe region and a second facet is providedon the second end of the laser stripe region. The device has an n-typecladding region overlying the semipolar surface. The device has anactive region comprising at least one active layer region overlying then-type cladding region. The at least one active region comprises aquantum well region or a double hetero-structure region. A p-typecladding region is overlying the active region. In certain embodiments,the emitted laser radiation is linearly polarized, in certainembodiments, circularly polarized, and in certain embodiments, theemitted laser radiation is elliptically polarized.

In another example, the invention provides a laser device. The deviceincludes a gallium and nitrogen containing substrate having a semipolarsurface configured on one of either a (60-6-1), (60-61), (50-5-1),(50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21),a (30-3-2), a (30-32), and/or an offcut orientation. An array of Nsingle lateral mode stripes is formed overlying the semipolar surface.Each of the single lateral mode laser stripes is characterized by acavity orientation substantially parallel to the projection of thec-direction and each of the single lateral mode stripes has a lengthranging from 20 μm to 500 μm. The device includes a width ranging fromabout 0.5 μm to about 2.5 μm. The device operates in the single lateralmode for each of the stripes. Each of the single lateral mode stripesemits a laser beam having a first polarization state and a secondpolarization state. The first polarization state is orthogonal to thesecond polarization state. The laser device is configured to emit in asubstantially polarized state having a primary polarization state and asecondary polarization state wherein the second polarization state is atleast less than 15% that of the primary polarization state.

In an alternative example, the invention provides a laser device. Thedevice includes a gallium and nitrogen containing material having asemipolar surface configured on one of either a (60-6-1), (60-61),(50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a(20-21), a (30-3-2), a (30-32), and/or an offcut orientation. The devicehas a laser stripe region formed overlying a portion of the semipolarsurface. The laser stripe region is characterized by a cavityorientation substantially parallel to the projection of the c-direction.The laser stripe region has a first end and a second end. The laserstripe is characterized by a variable width. The variable width can havea narrow region to provide a single lateral optical mode and a wideregion that is greater than about 3 μm. The device has an n-typecladding region overlying the semipolar surface and an active regioncomprising at least one active layer region overlying the n-typecladding region. The active layer region comprises a quantum well regionor a double hetero-structure region. In other examples, the width iscontinuous and has varying width dimensions. The device has a p-typecladding region overlying the active region. The device is configured toemit a laser beam having a first polarization state and a secondpolarization state wherein the first polarization state is orthogonal tothe second polarization state. The emitted laser beam is characterizedby a polarization ratio between the power emitted in the firstpolarization state and the power emitted in the second polarizationstate of 0.85 and greater.

In an alternative example, the present invention provides a laserdevice. The device includes a gallium and nitrogen containing materialhaving a semipolar surface configured on one of either a (60-6-1),(60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a(20-2-1), a (20-21), a (30-3-2), a (30-32), and/or an offcutorientation. The laser beam emitted by the device is characterized by across-polarized emission such that at least 15% of the emission is in asecond polarization state. In certain embodiments, the device has anoutput power of over 125 mW and the polarization ratio between the firstpolarization state and the second polarization state is 0.85 andgreater.

In another example, the invention provides a method of manufacturing anoptical device. The method includes providing a gallium and nitrogencontaining semipolar substrate member having a crystalline surfaceregion. The semipolar surface is configured on one of either a (60-6-1),(60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a(20-2-1), a (20-21), a (30-3-2), a (30-32), and/or an offcutorientation. The gallium and nitrogen containing substrate member ischaracterized by a dislocation density of less than 10E7 cm⁻². Themethod includes forming a gallium and nitrogen containing n-typecladding layer overlying the surface region. The n-type cladding layerhas a thickness from 300 nm to 6000 nm with an n-type doping level of1E17 cm⁻³ to 6E18 cm⁻³. The method includes forming an n-side separateconfining heterostructure (SCH) waveguiding layer overlying the n-typecladding layer. The n-side SCH waveguide layer comprises at leastgallium, indium, and nitrogen with molar fraction of InN of between 1%and 12% and has a thickness from 20 nm to 150 nm. The method includesforming an active region overlying the n-side SCH waveguide layer. Theactive region comprises at least two quantum well regions, but in apreferred embodiment includes more quantum wells such a 4 to 6 quantumwells. The quantum wells comprise InGaN with a thickness of about 2 nmto about 8 nm and the quantum wells regions are separated by barrierregions. The barrier regions are comprised of at least gallium andnitrogen with a thickness of about 2.0 nm to about 25 nm. The methodincludes forming a p-type gallium and nitrogen containing cladding layeroverlying the multiple quantum well active region. The p-type claddinglayer has a thickness from 300 nm to 1000 nm with a p-type doping levelof 1E17 cm³ to 5E19 cm³. The method includes forming a p++ gallium andnitrogen containing contact layer overlying the p-type cladding layer.The p++ gallium and nitrogen containing contact layer has a thicknessfrom 10 nm to 120 nm with a p-type doping level of 1E19 cm³ to 1E22 cm³.The method includes forming a waveguide member, which is alignedsubstantially in the projection of the c-direction. The waveguide membercomprises of a first end and a second end. The device has an electronblocking layer overlying the p-side guide layer. The electron blockinglayer is comprised of AlGaN with molar fraction of AlN of between 4% and22% and has a thickness from 5 nm to 25 nm and doped with magnesium.

In another example, the invention provides a method for manufacturing anoptical device. The method includes providing a gallium and nitrogencontaining semipolar substrate member having a crystalline surfaceregion, the semipolar surface being configured on one of either a(60-6-1), (60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a(30-31), a (20-2-1), a (20-21), a (30-3-2), a (30-32), and/or an offcutorientation. The gallium and nitrogen containing substrate member ischaracterized by a dislocation density of less than 10⁷ cm⁻². The methodincludes forming an n-type cladding layer comprising a first ternaryAlGaN alloy or a first quaternary AlInGaN alloy. The first alloycomprises at least an aluminum bearing species, a gallium bearingspecies, and a nitrogen bearing species overlying the surface region.The n-type cladding layer has a thickness from 100 nm to 6000 nm with ann-type doping level of 5E16 cm⁻³ to 6E18 cm⁻³. The method includesforming an n-side separate confining heterostructure (SCH) waveguidinglayer overlying the n-type cladding layer. The n-side SCH waveguidelayer is comprised of InGaN with molar fraction of InN of between 1% and10% and having a thickness from 30 nm to 150 nm. The method includesforming a multiple quantum well active region overlying the n-side SCHwaveguide layer. The multiple quantum well active region is comprised oftwo to five 2 nm to 8 nm InGaN quantum wells separated by 2 nm to 20 nmgallium and nitrogen containing barrier layers. The method includesforming a p-type cladding layer comprising a second ternary AlGaN alloyor quaternary AlInGaN alloy overlying the active region. The p-typecladding layer has a thickness from 250 nm to 1000 nm and comprises ap-type doping species including magnesium at a concentration of 1E17cm⁻³ to 4E19 cm⁻³. The method includes forming a p++ gallium andnitrogen containing contact layer overlying the p-type cladding layer.The p++ gallium and nitrogen containing contact layer has a thicknessfrom 10 nm to 140 nm and comprises a p-type doping species includingmagnesium at a concentration of 1E19 cm⁻³ to 1E22 cm⁻³. The methodincludes forming a waveguide member, which is aligned substantially inthe projection of the c-direction. The waveguide region comprises of afirst end and a second end. The first end comprises a first facet andthe second end comprising a second facet. The waveguide member has afirst edge region formed on a first side of the waveguide member. Thefirst edge region has a first etched surface formed on the first edgeregion. The waveguide member having a second edge region formed on asecond side of the waveguide member and the second edge region has asecond etched surface formed on the second edge region. In this example,the waveguide member is provided between the first facet and the secondfacet, the waveguide member having a length of greater than 20 micronsand less than about 500 microns and the offcut of the semipolarorientation is between +/−5 degrees toward a c-plane and/or between+/−10 degrees towards an a-plane.

In a first aspect, laser devices are provided comprising: a gallium andnitrogen containing material having a semipolar surface configured on anoffcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51) plane, a (40-4-1) plane, (40-41) plane, a(30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a(30-3-2), or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to theprojection of the c-direction, the laser stripe region having a firstend and a second end; the laser stripe region characterized by a lengthless than 300 μm; a first facet provided on the first end of the laserstripe region; a second facet provided on the second end of the laserstripe region; an n-type cladding region overlying the semipolarsurface; an active region comprising at least one active layer regionoverlying the n-type cladding region, the active region comprising aquantum well region or a double hetero-structure region; and a p-typecladding region overlying the active region; wherein the laser striperegion is characterized by a width configured to emit a laser beamhaving a selected ratio of a first polarization state and a secondpolarization state.

In a second aspect, laser devices are provided comprising: a gallium andnitrogen containing substrate having a semipolar surface configured onan offcut orientation to one of either a (30-3-1) plane, a (30-31)plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32)plane; an array of N single lateral mode laser stripes formed overlyingthe semipolar surface, wherein: each of the laser stripes ischaracterized by a cavity orientation substantially parallel to theprojection of a c-direction, each of the laser stripes having a lengthless than 300 μm; each of the laser stripes is characterized by a widthranging from about 0.5 μm to about 2.5 μm; each of the laser stripes isconfigured to operate in a single lateral mode; each of the laserstripes is configured to emit a laser beam characterized by a firstpolarization state and a second polarization state, wherein the firstpolarization state is orthogonal to the second polarization state; andthe laser device is configured to emit a plurality of laser beams, eachof the plurality of laser beams characterized by a primary polarizationstate and a secondary polarization state, wherein a power emitted in thesecond polarization state is at less than 15% of a power emitted in thefirst polarization state.

In a third aspect, laser devices are provided comprising: a gallium andnitrogen containing material having a semipolar surface configured on anoffcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51), a (40-4-1) plane, a (40-41) plane, a (30-3-1)plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2)plane, or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to theprojection of the c-direction, the laser stripe region having a firstend and a second end; a first facet provided on the first end of thelaser stripe region; a second facet provided on the second end of thelaser stripe region; an n-type cladding region overlying the semipolarsurface; an active region comprising at least one active layer regionoverlying the n-type cladding region; the active region comprising aquantum well region or a double hetero-structure region; and a p-typecladding region overlying the active region; a width characterizing thelaser stripe region configured to emit a laser beam having a firstpolarization state and a second polarization state, the firstpolarization state being orthogonal to the second polarization state andthe first polarization state being the primary polarization state; and apolarization ratio of the laser beam characterizing a cross-polarizedemission such that at least 15% of an emitted power is in the secondpolarization state.

In a fourth aspect, methods of manufacturing optical devices areprovided, the methods comprising: providing a gallium and nitrogencontaining semipolar substrate member having a crystalline surfaceregion; the semipolar surface being configured on an offcut orientationto one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a(50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a(30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a(30-32) plane; the gallium and nitrogen containing substrate membercharacterized by a dislocation density of less than 10⁷ cm⁻²; forming agallium and nitrogen containing n-type cladding layer overlying thesurface region, the n-type cladding layer having a thickness from 300 nmto 6000 nm with an n-type doping level of 1E17 cm⁻³ to 6E18 cm⁻³;forming an n-side separate confining heterostructure (SCH) waveguidinglayer overlying the n-type cladding layer, the n-side SCH waveguidelayer comprising gallium, indium, and nitrogen with a molar fraction ofInN of between 1% and 12% and having a thickness from 20 nm to 150 nm;forming an active region overlying the n-side SCH waveguiding layer, theactive region comprising at least two quantum wells, the at least twoquantum wells comprising InGaN with a thickness of about 2 nm to about 8nm; the at least two quantum wells separated by barrier regions, thebarrier regions comprising gallium and nitrogen with a thickness ofabout 2.5 nm to about 25 nm; forming a p-type gallium and nitrogencontaining cladding layer overlying the active region, the p-typecladding layer having a thickness from 300 nm to 1000 nm with a p-typedoping level of 1E17 cm⁻³ to 5E19 cm⁻³; forming a p++ gallium andnitrogen containing contact layer overlying the p-type cladding layer,the p++ gallium and nitrogen containing contact layer having a thicknessfrom 10 nm to 120 nm with a p-type doping level of 1E19 cm⁻³ to 1E22cm⁻³; and forming a waveguide member overlying the p++ gallium andnitrogen contact layer, the waveguide member aligned substantially inthe projection of the c-direction, the waveguide member comprising afirst end and a second end, the waveguide member being characterized bya length of less than 300 microns.

In a fifth aspect, methods for manufacturing optical devices areprovided, the methods comprising: providing a gallium and nitrogencontaining semipolar substrate member having a crystalline surfaceregion, the semipolar surface being configured on an offcut orientationto one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a(50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a(30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a(30-32) plane, the gallium and nitrogen containing semipolar substratemember being characterized by a dislocation density of less than 10⁷cm⁻²; forming an n-type cladding layer comprising a first ternary AlGaNalloy or a first quaternary AlInGaN alloy, the first alloy comprising atleast an aluminum bearing species, a gallium bearing species, and anitrogen bearing species overlying the surface region, the n-typecladding layer having a thickness from 100 nm to 6,000 nm with an n-typedoping level of 5E16 cm⁻³ to 6E18 cm⁻³; forming an n-side separateconfining heterostructure (SCH) waveguiding layer overlying the n-typecladding layer, the n-side SCH waveguiding layer comprising InGaN with amolar fraction of InN of between 1% and 10% and having a thickness from30 nm to 150 nm; forming a multiple quantum well active region overlyingthe n-side SCH waveguiding layer, the multiple quantum well activeregion comprising two to five, 2 nm to 8 nm thick, InGaN quantum wellsseparated by 3 nm to 20 nm thick gallium and nitrogen containing barrierlayers; forming a p-type cladding layer comprising a second ternaryAlGaN alloy or quaternary AlInGaN alloy overlying the multiple quantumwell active region, the p-type cladding layer having a thickness from250 nm to 1,000 nm and comprising a p-type doping species includingmagnesium at a concentration of 1E17 cm⁻³ to 4E19 cm⁻³; forming a p++gallium and nitrogen containing contact layer overlying the p-typecladding layer, the p++ gallium and nitrogen containing contact layerhaving a thickness from 10 nm to 140 nm and comprising a p-type dopingspecies including magnesium at a concentration of 1E19 cm⁻³ to 1E22cm⁻³; and forming a waveguide member, the waveguide member being alignedsubstantially in the projection of the c-direction, the waveguide membercomprising of a first end and a second end, the first end comprising afirst facet, the second end comprising a second facet, the waveguidemember provided between the first facet and the second facet and beingcharacterized by a length of less than 300 microns, the waveguide memberhaving a first edge region formed on a first side of the waveguidemember, the first edge region having a first etched surface formed onthe first edge region, the waveguide member having a second edge regionformed on a second side of the waveguide member, the second edge regionhaving a second etched surface formed on the second edge region.

In a sixth aspect, methods of manufacturing optical devices areprovided, the methods comprising: providing a gallium and nitrogencontaining semipolar substrate member having a crystalline surfaceregion; the semipolar surface being configured on an offcut orientationto one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a(50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a(30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a(30-32) plane; the gallium and nitrogen containing semipolar substratemember characterized by a dislocation density of less than 10⁷ cm⁻²;forming a gallium and nitrogen containing n-type cladding layeroverlying the surface region, the n-type cladding layer having athickness from 300 nm to 6000 nm with an n-type doping level of 1E17cm⁻³ to 6E18 cm⁻³, the n-type cladding layer being substantially freefrom an aluminum bearing material; forming an n-side separate confiningheterostructure (SCH) waveguiding layer overlying the n-type claddinglayer, the n-side SCH waveguiding layer comprising gallium, indium, andnitrogen with a molar fraction of InN of between 1% and 12% and having athickness from 20 nm to 150 nm; forming an active region overlying then-side SCH waveguiding layer, the active region comprising at least twoquantum well regions, the at least two quantum wells comprising InGaNwith a thickness of about 2 nm to about 8 nm; the at least two quantumwells separated by barrier regions, the barrier regions comprising leastgallium and nitrogen with a thickness of about 2.5 nm to about 25 nm;forming a p-type gallium and nitrogen containing cladding layeroverlying the active region, the p-type cladding layer having athickness from 300 nm to 1000 nm with a p-type doping level of 1E17 cm⁻³to 5E19 cm⁻³; forming a p++ gallium and nitrogen containing contactlayer overlying the p-type gallium and nitrogen containing claddinglayer, the p++ gallium and nitrogen containing contact layer having athickness from 10 nm to 120 nm with a p-type doping level of 1E19 cm⁻³to 1E22 cm⁻³; and forming a waveguide member, the waveguide memberaligned substantially in the projection of the c-direction, thewaveguide member comprising a first end and a second end, the waveguidemember being characterized by a length of less than 300 microns.

The present invention achieves these benefits and others in the contextof known process technology. However, a further understanding of thenature and advantages of the present invention may be realized byreference to the latter portions of the specification and attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram of laser device according to certainembodiments of the present invention.

FIG. 2 is a simplified diagram of laser device according to certainembodiments of the present invention.

FIGS. 3A and 3B presents the measured gain spectra and extracted peakmodal gain versus current density, respectively, for equivalent laserstructures formed on m-plane and on the (30-3-1) semipolar plane showingnearly 3 times greater gain on (30-3-1) than on nonpolar.

FIG. 4 presents a simulation of threshold modal gain versus cavitylength of for gallium and nitrogen containing LDs with back facetcoatings of 99% reflectivity and no front facet coating and 75%reflectivity.

FIG. 5 presents simulated threshold current density versus cavity lengthfor identical laser structures formed on nonpolar m-plane and semipolar(30-3-1) plane assuming no front facet coating.

FIG. 6 presents simulated threshold current density versus cavity lengthfor identical laser structures formed on nonpolar m-plane and semipolar(30-3-1) plane assuming a front facet coating with a reflectivity of75%.

FIG. 7 shows a schematic image of a multi-stripe laser chip depictingthe cavity width and length.

FIG. 8 is a schematic diagram of a cross-section of a multi-stripe laserconfiguration.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

This present invention is directed to optical devices and relatedmethods. In particular, the present invention provides a method anddevice for emitting electromagnetic radiation using semipolar galliumcontaining substrates such as GaN, AN, InN, InGaN, Al GaN, and AlInGaN,and others. Merely by way of example, the invention can be applied tooptical devices, lasers, light emitting diodes, solar cells,photoelectrochemical water splitting and hydrogen generation,photodetectors, integrated circuits, and transistors, among otherdevices.

Forming laser diodes on semipolar orientations of gallium and nitrogencontaining material (e.g., GaN) can be advantageous. Such lasers mayinclude long wavelength emission, high gain properties, improvedmaterial quality, and/or increased design flexibility over alternativeplanes such as the conventional polar c-plane or even the nonpolarm-plane or polar c-plane. For example, we have fabricated true greenlaser diodes on the (20-21) semipolar plane and found that the (30-3-1)semipolar plane offers narrower full width at half maximum (FWHM)emission spectra and higher gain compared to the nonpolar m-plane in theblue regime, as described in U.S. application Ser. No. 12/883,093 filedon Sep. 15, 2010, which is incorporated by reference.

As an example, FIG. 1 is a simplified schematic diagram of semipolarlaser diode with the cavity aligned in the projection of c-directionwith cleaved or etched mirrors. Example of projection of c-directionoriented laser diode stripe on semipolar (30-3-1) substrate with cleavedor etched mirrors. As shown, the optical device includes a galliumnitride substrate member having a semipolar crystalline surface regioncharacterized by an orientation of about 9 degrees to about 12.5 degreestowards (000-1) from the m-plane.). In an embodiment, the galliumnitride substrate member is a bulk GaN substrate characterized by havinga semipolar crystalline surface region, but can be others. In anembodiment, the bulk GaN substrate has a surface dislocation densitybelow 10⁵ cm⁻² or 10⁵ to 10⁷ cm⁻². It should be noted that homoepitaxialgrowth on bulk GaN is generally better than hetero-epitaxy growth. Thenitride crystal or wafer may comprise Al_(x)In_(y)Ga_(1-x-y)N, where0≦x, y, x+y≦1. In an embodiment, the nitride crystal comprises GaN. Inone or more embodiments, the GaN substrate has threading dislocations,at a concentration between about 10⁵ cm⁻² and about 10⁸ cm⁻², in adirection that is substantially orthogonal or oblique with respect tothe surface. As a consequence of the orthogonal or oblique orientationof the dislocations, the surface dislocation density is below about 10⁵cm⁻² or below about 10⁷ cm⁻² others such as those ranging from about10⁵-10⁸ cm⁻². In alternative example, is a projection of the c-directionoriented laser diode stripe on semipolar (20-21) substrate with cleavedor etched mirrors. The optical device includes a gallium nitridesubstrate member having a semipolar crystalline surface regioncharacterized by an orientation of about 13 degrees to about 17 degreestowards (0001) from the m-plane.). In an embodiment, the gallium nitridesubstrate member is a bulk GaN substrate characterized by having asemipolar crystalline surface region, but can be others. In anembodiment, the bulk GaN substrate has a surface dislocation densitybelow 10⁵ cm⁻² or 10⁵ to 10⁷ cm⁻².

In an embodiment, the device has a laser stripe region formed overlyinga portion of the semipolar crystalline orientation surface region. In anembodiment, the laser stripe region is characterized by a cavityorientation that is substantially parallel to the projection of thec-direction. In an embodiment, the laser stripe region has a first endand a second end.

In an embodiment, the device has a first facet provided on the first endof the laser stripe region and a second facet provided on the second endof the laser stripe region. In one or more embodiments, the first facetis substantially parallel with the second facet. Mirror surfaces areformed on each of the surfaces. The first facet comprises a first mirrorsurface. In an embodiment, the first mirror surface is provided by ascribing and breaking process or alternatively by etching techniquesusing etching technologies such as reactive ion etching (RIE),inductively coupled plasma etching (ICP), or chemical assisted ion beametching (CAIBE), or other method. Any suitable scribing process can beused, such as a diamond scribe or laser scribe or combinations. In anembodiment, the first mirror surface comprises a reflective coating. Inan embodiment, the reflective coating can be deposited using, forexample, e-beam evaporation, thermal evaporation, RF sputtering, DCsputtering, ECR sputtering, ion beam deposition, Ion AssistedDeposition, reactive ion plating, any combinations, and the like. Instill other embodiments, surface passivation may be used to the exposedsurface prior to coating. The reflective coating is selected fromsilicon dioxide, hafnia, and titania, tantalum pentoxide, zirconia,including combinations, and the like. Preferably, the reflective coatingis highly reflective and includes a coating of silicon dioxide andtantalum pentoxide, which has been deposited using electron beamdeposition. Depending upon the embodiment, the first mirror surface canalso comprise an anti-reflective coating. Additionally, the facets canbe cleaved or etched or a combination of them.

Also in an embodiment, the second facet comprises a second mirrorsurface. The second mirror surface is provided by a scribing andbreaking process according to an embodiment or alternatively by etchingtechniques using etching technologies such as reactive ion etching(RIE), inductively coupled plasma etching (ICP), or chemical assistedion beam etching (CAIBE), or other method. Preferably, the scribing isdiamond scribed or laser scribed or the like. In an embodiment, thesecond mirror surface comprises a reflective coating, such as silicondioxide, hafnia, titania, tantalum pentoxide, zirconia, aluminum oxide,combinations, and the like. In an embodiment, the second mirror surfacecomprises an anti-reflective coating, such alumina or aluminum oxide. Inan embodiment, the coating can be formed using electron beam deposition,thermal evaporation, RF sputtering, DC sputtering, ECR sputtering, ionbeam deposition, ion assisted deposition, reactive ion plating, anycombinations, and the like. In still other embodiments, the presentmethod may provide surface passivation to the exposed surface prior tocoating.

In an embodiment, the laser stripe has a length and width. The lengthranges from about 20 microns to about 500 microns. The stripe also has awidth ranging from about 0.5 microns to about 50 microns, but can beother dimensions. In an embodiment, the stripe can also be about 3 to 25microns wide for a high power multi-lateral-mode device or about 1 to 2microns for a single lateral mode laser device. In an embodiment, thewidth is substantially constant in dimension, although there may beslight variations. The width and length are often formed using a maskingand etching process, which are commonly used in the art.

In an embodiment, the device is also characterized by a spontaneouslyemitted light that is polarized in substantially perpendicular to theprojection of the c-direction (in the a-direction). That is, the deviceperforms as a laser or the like. In an embodiment, the spontaneouslyemitted light is characterized by a polarization ratio of greater than0.2 to about 1 perpendicular to the c-direction. In an embodiment, thespontaneously emitted light is characterized by a wavelength rangingfrom about 400 nanometers to yield a violet emission, a blue emission, agreen emission, and/or others. In certain embodiments, the light can beemissions ranging from violet 395 nm to 420 nm; blue 430 nm to 470 nm;green 500 nm to 550 nm; or others, which may slightly vary dependingupon the application. In an embodiment, the spontaneously emitted lightis highly polarized and is characterized by a polarization ratio ofgreater than 0.4. In an embodiment, the emitted light is characterizedby a polarization ratio that is preferred.

FIG. 2 is a simplified schematic cross-sectional diagram illustrating alaser diode structure according to embodiments of the presentdisclosure. As shown, the laser device includes gallium nitridesubstrate 203, which has an underlying n-type metal back contact region201. In an embodiment, the metal back contact region is made of asuitable material such as those noted below and others.

In an embodiment, the device also has an overlying n-type galliumnitride layer 205, an active region 207, and an overlying p-type galliumnitride layer structured as a laser stripe region 211. Additionally, thedevice also includes an n-side separate confinement heterostructure(SCH) 206, p-side guiding layer or SCH 208, p-AlGaN EBL 209, among otherfeatures. In an embodiment, the device also has a p++ type galliumnitride material 213 to form a contact region. In an embodiment, the p++type contact region has a suitable thickness and may range from about 10nm to 50 nm, or other thicknesses. In an embodiment, the doping levelcan be higher than the p-type cladding region and/or bulk region. In anembodiment, the p++ type region has doping concentration ranging fromabout 10¹⁹ Mg/cm³ to 10²¹ Mg/cm³, or others. The p++ type regionpreferably causes tunneling between the semiconductor region andoverlying metal contact region. In an embodiment, each of these regionsis formed using at least an epitaxial deposition technique of metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE),or other epitaxial growth techniques suitable for GaN growth. In anembodiment, the epitaxial layer is a high quality epitaxial layeroverlying the n-type gallium nitride layer. In some embodiments, thehigh quality layer is doped, for example, with Si or O to form n-typematerial, with a dopant concentration between about 10¹⁶ cm⁻³ and 10²⁰cm⁻³.

In an embodiment, an n-type Al_(u)In_(v)Ga_(1-u-v)N layer, where 0≦u, v,u+v≦1, is deposited on the substrate. In an embodiment, the carrierconcentration may lie in the range between about 10¹⁶ cm⁻³ and 10²⁰cm⁻³. The deposition may be performed using metalorganic chemical vapordeposition (MOCVD) or molecular beam epitaxy (MBE).

As an example, the bulk GaN substrate is placed on a susceptor in anMOCVD reactor. After closing, evacuating, and back-filling the reactor(or using a load lock configuration) to atmospheric pressure, thesusceptor is heated to a temperature between about 900 degrees Celsiusto about 1200 degrees Celsius in the presence of a nitrogen-containinggas. As an example, the carrier can be hydrogen or nitrogen or others.In an embodiment, the susceptor is heated to approximately 1100 degreesCelsius under flowing ammonia. A flow of a gallium-containingmetalorganic precursor, such as trimethylgallium (TMG) ortriethylgallium (TEG) is initiated, in a carrier gas, at a total ratebetween approximately 1 and 50 standard cubic centimeters per minute(sccm). The carrier gas may comprise hydrogen, helium, nitrogen, orargon. The ratio of the flow rate of the group V precursor (e.g.,ammonia) to that of the group III precursor (trimethylgallium,triethylgallium, trimethylindium, trimethylaluminum) during growth isbetween about 2,000 and about 12,000. A flow of disilane in a carriergas, with a total flow rate of between about 0.1 and 10 sccm isinitiated.

In an embodiment, the laser stripe region is made of the p-type galliumnitride layer 211. In an embodiment, the laser stripe is provided by anetching process selected from dry etching or wet etching. In anembodiment, the etching process is dry, but can be others. As anexample, the dry etching process is an inductively coupled plasmaprocess using chlorine bearing species or a reactive ion etching processusing similar chemistries or combination of ICP and RIE, among othertechniques. Again as an example, the chlorine bearing species arecommonly derived from chlorine gas or the like. The device also has anoverlying dielectric region, which exposes 213 contact region, which ispreferably a p++ gallium nitride region. In an embodiment, thedielectric region is an oxide such as silicon dioxide or siliconnitride, but can be others, such as those described in more detailthroughout the present specification and more particularly below. Thecontact region is coupled to an overlying metal layer 215. The overlyingmetal layer is a multilayered structure containing gold and platinum(Ni/Au), but can be others such as gold and palladium (Pd/Au), gold,titanium, and palladium (Pd/Ti/Au) or gold and nickel (Pt/Au). In analternative embodiment, the metal layer comprises Pd/Au formed usingsuitable techniques. In an embodiment, the Ni/Au is formed viaelectron-beam deposition, sputtering, or any like techniques. Thethickness includes nickel material ranging in thickness from about 50 toabout 100 nm and gold material ranging in thickness from about 100Angstroms to about 1-3 microns, and others.

In an embodiment, the dielectric region can be made using a suitabletechnique. As an example, the technique may include reactively sputterof SiO₂ using an undoped polysilicon target (99.999% purity) with O₂ andAr. In an embodiment, the technique uses RF magnetron sputter cathodesconfigured for static deposition; sputter target; throw distance;pressure: 1-5 mT or about 2.5 mT, power: 300 to 400 W; flows: 2-3.-9sccm O₂, 20-50 sccm, Ar, deposition thickness: 1000-2500 A, and mayinclude other variations. In an embodiment, deposition may occur usingnon-absorbing, nonconductive films, e.g., Al₂O₃, Ta₂O₅, SiO₂, Ta₂O₅,ZrO₂, TiO₂, HfO₂, NbO₂. Depending upon the embodiment, the dielectricregion may be thinner, thicker, or the like. In other embodiments, thedielectric region can also include multilayer coatings, e.g., 1000 A ofSiO₂ capped with 500 A of Al₂O₃. Deposition techniques can include,among others, ebeam evaporation, thermal evaporation, RF Sputter, DCSputter, ECR Sputter, Ion Beam Deposition, Ion Assisted Deposition,reactive ion plating, combinations, and the like.

In an embodiment, the laser device has active region 207. The activeregion can include one to twenty quantum well regions according to oneor more embodiments. As an example, following deposition of the n-typeAl_(u)In_(v)Ga_(1-u-v)N layer for a predetermined period of time, so asto achieve a predetermined thickness, an active layer is deposited. Theactive layer may comprise a single quantum well or a multiple quantumwell, with 1-20 quantum wells. Preferably, the active layer may includeabout 3-7 quantum wells or more preferably 4-6 quantum wells or others.The quantum wells may comprise InGaN wells and GaN barrier layers. Inother embodiments, the well layers and barrier layers compriseAl_(w)In_(x)Ga_(1-w-x)N and Al_(y)In_(z)Ga_(1-y-z)N, respectively, where0≦w, x, y, z, w+x, y+z≦1, where w<u, y and/or x>v, z so that the bandgapof the well layer(s) is less than that of the barrier layer(s) and then-type layer. The well layers and barrier layers may each have athickness between about 1 nm and about 40 nm. In an embodiment, each ofthe thicknesses is preferably 2 nm-8 nm. In an embodiment, each wellregion may have a thickness of about 4 nm to 7 nm and each barrierregion may have a thickness of about 2 nm to about 5 nm, among others.In another embodiment, the active layer comprises a doubleheterostructure, with an InGaN or Al_(w)In_(x)Ga_(1-w-x)N layer about 10nm to 100 nm thick surrounded by GaN or Al_(y)In_(z)Ga_(1-y-z)N layers,where w<u, y and/or x>v, z. The composition and structure of the activelayer are chosen to provide light emission at a preselected wavelength.The active layer may be left undoped (or unintentionally doped) or maybe doped n-type or p-type.

In an embodiment, the active region can also include an electronblocking region, and a separate confinement heterostructure. In anembodiment, the separate confinement heterostructure (SCH) can includeAlInGaN or preferably InGaN, but can be other materials. The SCH isgenerally comprised of material with an intermediate index between thecladding layers and the active layers to improve confinement of theoptical mode within the active region of the laser device according toan embodiment. In one or more embodiments, the SCH layers have apreferred thickness, impurity, and configuration above and below theactive region to confine the optical mode. Depending upon theembodiment, the upper and lower SCH can be configured differently or thesame. The electron blocking region can be on either side or both sidesof the SCH positioned above the active region according to anembodiment. In an embodiment, the SCH can range from about 10 nm toabout 150 nm, and preferably about 40 to 100 nm for the lower SCHregion. In the upper SCH region, the thickness ranges from about 20 to50 nm in an embodiment. As noted, the SCH is preferably InGaN havingabout 2% to about 5% indium or 5% to about 10% by atomic percentaccording to an embodiment.

In some embodiments, an electron blocking layer is preferably deposited.In an embodiment, the electron blocking layer comprises a gallium andnitrogen containing material including magnesium at a concentration ofabout 10¹⁶ cm⁻³ to about 10²² cm⁻³. The electron-blocking layer maycomprise Al_(s)In_(t)Ga_(1-s-t)N, where 0≦s, t, s+t≦1, with a higherbandgap than the active layer, and may be doped p-type. In one specificembodiment, the electron blocking layer comprises AlGaN with an Alcomposition ranging from 5% to 20%. In another embodiment, the electronblocking layer may not contain Al. In another embodiment, the electronblocking layer comprises an AlGaN/GaN super-lattice structure,comprising alternating layers of AlGaN and GaN, each with a thicknessbetween about 0.2 nm and about 5 nm.

As noted, the p-type gallium nitride structure, which can be a p-typedoped Al_(q)In_(r)Ga_(1-q-r)N, where 0≦q, r, q+r≦1, layer is depositedabove the active layer. The p-type layer may be doped with Mg, to alevel between about 10¹⁶ cm⁻³ and 10²² cm⁻³, and may have a thicknessbetween about 5 nm and about 1000 nm. The outermost 5 nm to 70 nm of thep-type layer may be doped more heavily than the rest of the layer, so asto enable an improved electrical contact. In an embodiment, the laserstripe is provided by an etching process selected from dry etching orwet etching. In an embodiment, the etching process is dry, but can beothers. The device also has an overlying dielectric region, whichexposes 213 contact region. In an embodiment, the dielectric region isan oxide such as silicon dioxide, but can be others.

In an embodiment, the metal contact is made of suitable material. Thereflective electrical contact may comprise at least one of silver, gold,aluminum, nickel, platinum, rhodium, palladium, chromium, or the like.The electrical contact may be deposited by thermal evaporation, electronbeam evaporation, electroplating, sputtering, or another suitabletechnique. In an embodiment, the electrical contact serves as a p-typeelectrode for the optical device. In another embodiment, the electricalcontact serves as an n-type electrode for the optical device. Of course,there can be other variations, modifications, and alternatives.

In an embodiment, a ridge waveguide is fabricated using a certaindeposition, masking, and etching processes. In an embodiment, the maskis comprised of photoresist (PR) or dielectric or any combination ofboth and/or different types of them. The ridge mask is about 1 micronsto about 2.5 microns wide for single lateral mode applications or 2.5 μmto 30 μm wide for multimode applications. The ridge waveguide is etchedby ion-coupled plasma (ICP), reactive ion etching (RIE), chemicalassisted ion beam (CAIBE) etched, or other method. The etched surface is20 nm to 250 nm above the active region. A dielectric passivation layeris then blanket deposited by any number of commonly used methods in theart, such as sputter, e-beam, PECVD, or other methods. This passivationlayer can include SiO₂, Si₃N₄, Ta₂O₅, or others. The thickness of thislayer is 80 nm-400 nm thick. An ultrasonic process is used to remove theetch mask which is covered with the dielectric. This exposes the p-GaNcontact layer. P-contact metal is deposited by e-beam, sputter, or otherdeposition technique using a PR mask to define the 2D geometry. Thecontact layer can be Ni/Au but others can be Pt/Au or Pd/Au.

In one or more preferred embodiments, the present disclosure provides alaser structure without an aluminum bearing cladding region. In anembodiment, the laser device comprises a multi-quantum well activeregion having thin barrier layers. In one or more embodiments, theactive region comprises three or more quantum well structures. Betweeneach of the quantum well structures there may be a thin barrier layer,e.g., 7 nm and less, 6 nm and less, 5 nm and less, 4 nm and less, 3 nmand less, 2 nm and less. In an embodiment, the combination of thinbarrier layers in the multi-quantum well structures enables a lowvoltage (e.g., 6 volts and less) laser diode free from use of aluminumbearing cladding regions.

In an embodiment, the present disclosure provides an optical device. Theoptical device has a gallium and nitrogen containing substrate includinga (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a(30-31), a (20-2-1), a (20-21), a (30-3-2), a (30-32), and/or an offcutorientation, or offcuts thereof crystalline surface region orientation,which may be off-cut. The device preferably has an n-type claddingmaterial overlying the n-type gallium and nitrogen containing materialaccording to an embodiment. The n-type cladding material may be formedfrom GaN, AlGaN, InAlGaN, or a combination and ranges in thickness fromabout 1 μm to about 5 μm according to an embodiment. The n-type claddingmaterial may be doped with silicon or oxygen. The device also has anactive region comprising at least three quantum wells. Each of thequantum wells has a thickness of 3.0 nm and greater or 5.5 nm andgreater, and one or more barrier layers. Each of the barrier layers hasa thickness ranging from about 2 nm to about 4 nm or about 4 nm to about8 nm or about 8 nm to about 20 nm and is configured between a pair ofquantum wells according to an embodiment. At least one or each of thebarrier layers has a thickness ranging from about 2 nm to about 4 nm andis configured between a pair of quantum wells or adjacent to a quantumwell according to an embodiment. At least one or each of the barrierlayers has a thickness ranging from about 3.5 nm to about 6.5 nm and isconfigured between a pair of quantum wells or adjacent to a quantum wellaccording to an embodiment. Preferably, the device has a p-type claddingmaterial overlying the active region. Preferably, the p-type claddingmaterial may be formed from GaN, AlGaN, InAlGaN, or a combination andranges in thickness from about 0.4 μm to about 1 μm according to anembodiment. The p-type cladding material may be doped with magnesium. Inan embodiment, the active region is configured for a forward voltage ofless than about 6V or less than about 5V for the device for an outputpower of 60 mW or 100 mW and greater.

In yet an alternative embodiment, the present disclosure provides anoptical device. The device has a gallium and nitrogen containingsubstrate including a (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1),(40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21), a (30-3-2), a(30-32), and/or an offcut orientation. The device also has an n-typecladding material overlying the n-type gallium and nitrogen containingmaterial. The n-type cladding material may be formed from GaN, AlGaN,InAlGaN, or a combination of any of the foregoing, and may range inthickness from about 1 μm to about 5 μm according to an embodiment. Then-type cladding material may be doped with silicon or oxygen. The devicefurther has an active region comprising at least three quantum wells.Each of the quantum wells has a thickness of 2.0 nm and greater or 3.5nm and greater or 5 nm and greater and one or more barrier layersaccording to an embodiment. Each of the barrier layers has a thicknessranging from about 2 nm to about 4 nm or about 4 nm to about 8 nm orabout 8 nm to about 20 nm according to an embodiment. Each of thebarrier layers is configured between a pair of quantum wells accordingto one or more embodiments. At least one or each of the barrier layershas a thickness ranging from about 2 nm to about 5 nm and is configuredbetween a pair of quantum wells or adjacent to a quantum well accordingto an embodiment. At least one or each of the barrier layers has athickness ranging from about 4 nm to about 8 nm and is configuredbetween a pair of quantum wells or adjacent to a quantum well accordingto an embodiment. The device also has a p-type cladding materialoverlying the active region. Preferably, the p-type cladding materialmay be formed from GaN, AlGaN, InAlGaN, or a combination and ranges inthickness from about 0.4 μm to about 1 μm according to an embodiment.The p-type cladding material may be doped with magnesium. The deviceoptionally has a p-type material overlying the p-type cladding material.

In other embodiments, the invention provides yet an alternative opticaldevice, which has a gallium and nitrogen containing substrate includinga (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a(30-31), a (20-2-1), a (20-21), a (30-3-2), a (30-32), or offcutsthereof crystalline surface region orientation. An n-type claddingmaterial is overlying the n-type gallium and nitrogen containingmaterial. Preferably, the n-type cladding material is substantially freefrom an aluminum bearing material. The device has an active regioncomprising at least three quantum wells, each of which has a thicknessof 2.5 nm or 3.5 nm and greater. The device has one or more barrierlayers, each of which has a thickness ranging from about 2 nm to about 4nm or about 4 nm to about 8 nm or about 8 nm to about 20 nm in one ormore alternative embodiments. Preferably, each of the barrier layers isconfigured between a pair of quantum wells according to an embodiment.The device also has a p-type cladding material overlying the activeregion according to an embodiment. The p-type cladding material issubstantially free from an aluminum bearing material according to anembodiment. The device also has a p-type material overlying the p-typecladding material.

In other embodiments, the invention provides a method of fabricating anoptical device, which has a gallium and nitrogen containing substrateincluding a (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1), (40-41),(30-3-1), a (30-31), a (20-2-1), a (20-21), a (30-3-2), a (30-32), oroffcuts thereof crystalline surface region orientation. An n-typecladding material is overlying the n-type gallium and nitrogencontaining material. Preferably, the n-type cladding material issubstantially free from an aluminum bearing material. The methodincludes forming an active region comprising at least three quantumwells, each of which has a thickness of 2.5 nm or 3.5 nm and greater.The device has one or more barrier layers, each of which has an n-typeimpurity characteristic and a thickness ranging from about 2 nm to about4 nm or about 4 nm to about 8 nm or about 8 nm to about 20 nm in one ormore alternative embodiments. Preferably, each of the barrier layers isconfigured between a pair of quantum wells according to an embodiment.The method also includes forming a p-type cladding material overlyingthe active region according to an embodiment. The p-type claddingmaterial is substantially free from an aluminum bearing materialaccording to an embodiment. The method also includes forming a p-typematerial overlying the p-type cladding material.

In an embodiment, the present disclosure provides an optical device,such as a laser diode. The device has a gallium and nitrogen containingsubstrate including a (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1),(40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21), a (30-3-2), a(30-32), or offcuts thereof crystalline surface region orientation,which may be off-cut according to one or more embodiments. The devicehas an n-type cladding material overlying the n-type gallium andnitrogen containing material. The n-type cladding material may be formedfrom GaN, AlGaN, InAlGaN, or a combination of any of the forgoing andmay range in thickness from about 1 μm to about 5 μm according to anembodiment. The n-type cladding material may be doped with silicon oroxygen. The device also has an active region comprising at least threequantum wells. In an embodiment, each of the quantum wells has athickness of 2.0 nm or 3.5 nm and greater and one or more barrier layersaccording to an embodiment. Each of the barrier layers has a n-typecharacteristic and a thickness ranging from about 2 nm to about 4.5 nmin an embodiment. Each of the barrier layers has a p-type characteristicand a thickness ranging from about 3.5 nm to about 7 nm in analternative specific embodiment. In an embodiment, each of the barrierlayers is configured between a pair of quantum wells. The device alsohas a p-type cladding material overlying the active region. Preferably,the p-type cladding material may be formed from GaN, AlGaN, InAlGaN, ora combination of any of the foregoing and may range in thickness fromabout 0.3 μm to about 1 μm according to an embodiment. The p-typecladding material may be doped with magnesium. And overlying p-typematerial is included. In an embodiment, the active region is configuredfor a forward voltage of less than about 6V or less than about 7V forthe device for an output power of 60 mW and greater. In otherembodiments for nonpolar m-plane devices or semipolar (60-6-1), (60-61),(50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a(20-21), a (30-3-2), a (30-32), or offcuts thereof planes, operable inthe blue (430 nm-475 nm) and green (505-530 nm), the present method andstructure include five (5) or more thick quantum wells of greater than 4nm or 5 nm in thickness and thin barriers that are 2-4 nm in thickness.

In one or more embodiments, the present disclosure includes a laserdiode substantially free from an aluminum containing cladding region.The diode that is free from aluminum containing cladding regions hasfaster growth times, and is not plagued with aluminum bearing materialsin the cladding. To form the laser diode without an aluminum containingcladding region, the present laser diode includes three or more quantumwells to provide enough confinement of the optical mode for sufficientgain to reach lasing. However, when the number of quantum wellsincreases in the active region, the forward voltage of the diode canincrease, as a tradeoff. We have determined that the forward voltage ofthe diode can be reduced in multi-quantum well active regions by way ofthe use of thin barriers on the order of 3 nm to 4 nm, which are muchthinner than conventional lasers such as those in Yoshizumi et al.,“Continuous-Wave operation of 520 nm Green InGaN-Based Laser Diodes onSemi-Polar {20-21} GaN Substrates,” Applied Physics Express, 2 (2009)092101. We have also determined that the forward voltage can be reducedin multi-quantum well active regions by adding p or n-type dopantspecies to the active region according to one or more other embodiments.Although any one or combination of these approached can be used, webelieve it would be preferable to use the thin barrier approach to avoidadding impurities to the active region. The impurities may changeoptical losses and alter the electrical junction placement according toone or more embodiments. Accordingly, the present disclosure provides alaser device and method with low voltage on (60-6-1), (60-61), (50-5-1),(50-51), (40-4-1), (40-41), (30-3-1), a (30-31), a (20-2-1), a (20-21),a (30-3-2), a (30-32), or offcuts thereof.

The device has a gallium and nitrogen containing substrate member havinga (60-6-1), (60-61), (50-5-1), (50-51), (40-4-1), (40-41), (30-3-1), a(30-31), a (20-2-1), a (20-21), a (30-3-2), a (30-32), or offcutsthereof crystalline surface region. The device has an n-type gallium andnitrogen containing cladding material. In an embodiment, the n-typegallium and nitrogen containing cladding material is substantially freefrom an aluminum species, which leads to imperfections, defects, andother limitations. The device also has an active region includingmultiple quantum well structures overlying the n-type gallium andnitrogen containing cladding material. In one or more preferredembodiments, the device also has thin barrier layers configured with themultiple well structures. The device has a p-type gallium and nitrogencontaining cladding material overlying the active region. In anembodiment, the p-type gallium and nitrogen containing cladding materialis substantially free from an aluminum species. The device preferablyincludes a laser stripe region configured from at least the activeregion and characterized by a cavity orientation substantially parallelto a projection of the c-direction. The laser stripe region has a firstend and a second end. The device also has a first cleaved or etchedfacet provided on the first end of the laser stripe region and a secondcleaved or etched facet provided on the second end of the laser striperegion. Depending upon the embodiment, the facets may be cleaved,etched, or a combination of cleaved and etched. In yet otherembodiments, the present device includes a gallium and nitrogencontaining electron-blocking region that is substantially free fromaluminum species. In yet other embodiments, the device does not includeany electron-blocking layer or yet in other embodiments, there is noaluminum in the cladding layers and/or electron blocking layer, althoughother embodiments include aluminum containing blocking layers. In stillother embodiments, the optical device and method are free from anyaluminum material, which leads to defects, imperfections, and the like.

In some preferred embodiments, the present method and structure issubstantially free from InAlGaN or aluminum bearing species in thecladding layers as conventional techniques, such as those in Yoshizumiet al., “Continuous-Wave operation of 520 nm Green InGaN-Based LaserDiodes on Semi-Polar {20-21} GaN Substrates,” Applied Physics Express 2(2009) 092101. That is, the present laser structure and method aresubstantially free from any aluminum species in the cladding region.Aluminum is generally detrimental. Aluminum often leads to introductionof oxygen in the reactor, which can act as non radiative recombinationcenters to reduce the radiative efficiency and introduce otherlimitations. We also determined that oxygen can compensate p-typedopants in the p-cladding to cause additional resistivity in the opticaldevice. In other aspects, we also determined that aluminum isdetrimental to the MOCVD reactor and can react or pre-react with othergrowth precursors. Use of aluminum containing cladding layers is alsocumbersome and can take additional time to grow. In fact, by usingsubstantially Al-free cladding layers MOCVD growth throughput can beincreased by 2-4× drastically reducing the cost associated with growth.Accordingly, it is believed that the aluminum cladding free laser methodand structure are generally more efficient to grow than conventionallaser structures.

As an example, FIG. 3A a presents the measured gain spectra at variouscurrent densities ranging from 0.26 kA/cm² to 5.29 kA/cm² for identicalblue laser epitaxial structures grown on m-plane and (30-3-1). As seenin the figure, the peak modal gain in the semipolar (30-3-1) structureis drastically higher than in the nonpolar structure at a given currentdensity. FIG. 3B presents the plots of peak modal gain versus currentdensity for these equivalent laser structures as extracted from the datain FIG. 3B. The slopes of the resulting plots provide the so calleddifferential gain in the laser cavity. The peak differential gain of thesemipolar (30-3-1) structures of 19.3 (cm⁻¹)/(kA/cm²) is about 3-timeshigher than of the nonpolar at 6.6 (cm⁻¹)/(kA/cm²). Such drasticallyhigher gain characteristics will lead to improved laser diodeperformance. For example an equivalent laser structure with identicallosses with 3 times the gain can have approximately ⅓ the thresholdcurrent density for an overall higher efficiency, as described in “GroupIII nitride laser diodes grown on a semipolar orientation of galliumnitride,” U.S. Ser. No. 61/664,084 filed on Jun. 25, 2012, which isincorporated by reference herein. Moreover, such high differential modalgain can enable ultra-short edge emitting laser cavity lengths of 50-200μm with low threshold current densities of below 3 kA/cm² in and goodhigh slope efficiencies of over 0.7 W/A, over 1.2 W/A, or over 1.5 W/A.

As the cavity length is reduced in an edge-emitting laser diode themirror loss is inversely proportionally increased. As the mirror loss isincreased the slope efficiency, the amount of unit optical output powerper unit of electrical input current, is increased such that more outputpower will be achieved for a given operating current. However, theincreased mirror loss will also result in an increased threshold modalgain such that the laser material will have to provide a higher gain toachieve threshold. If the differential gain characteristics dictated bythe material and waveguide design of the device are held constant thehigher required threshold modal gain would result in a higher thresholdcurrent density, meaning the input current required for the laser toachieve threshold would be increased. This degradation of increasedthreshold current counter acts the benefit achieved from higher slopeefficiency as the cavity length is reduced, and for a fixed cavity gainand internal loss characteristic it is this trade-off that sets theoptimal cavity length and the front and back mirror coatingreflectivities. For c-plane GaN edge emitting laser diodes operating inthe low power regime of less than 300 mW typical cavity lengths rangefrom 400 μm to 600 μm. This cavity length range is largely dictated bythe differential modal gain within the conventional c-plane laser diodeswhich sets the amount of cavity losses can be overcome at a reasonablethreshold current density of less than about 4 kA/cm² or less than about2 kA/cm².

As an example, FIG. 4 presents simulations of the threshold gain versuscavity length for edge emitting GaN-based lasers with an assumedinternal loss of 5 cm⁻¹. The solid curve represents a laser with a 99%reflective coating on the back facet and no reflective coating on thefront facet, while the dashed curve represents a laser with a 99%reflective coating on the back facet and a 75% reflective coating on thefront facet. The curves demonstrate that the threshold gain rapidlyincreases for cavity lengths shorter than 200 μm with no reflectivecoating on front facet and drastically increases for cavity lengthsshorter than 50 μm with a 75% reflective coating on front facet. Thisindicates that to achieve lasing at a low threshold current density thelaser diode must possess high differential modal gain to overcome thecavity loss to reach threshold.

In this invention we exploit the high modal gain of gallium and nitrogencontaining semipolar laser diodes to achieve ultra-short cavity lengthswith viable threshold current densities. With the high material gain andhigh confinement active region designs enabled in semipolar laser diodescavity lengths of less than 300 μm, less than 200 μm, less than 100 μm,and even less than 50 μm can be achieved. This breakthrough will breakthe paradigm of 450 μm to 600 μm cavity lengths currently used inc-plane devices and offer several advantages such as reduced cost,higher efficiency, and smaller form factor. For example, since the chiplength of a conventional linear-cavity edge emitting laser diode isconstrained by the length of the cavity, by reducing the cavity lengthin a GaN-based ˜100 mW edge emitting laser diode from the typical lengthof 500 μm to 600 μm to a length of only 100 μm a given wafer can yield5- to 6-times more laser chips. This can result in up to a 5- to 6-timesreduction in chip cost and enable ultra-low cost laser chips to enablenew markets.

FIG. 5 presents the simulated threshold current density dependence onlaser cavity length for blue LDs fabricated on the nonpolar m-plane(solid) orientation using the experimentally measured differential modalgain of 6.6 cm⁻¹/(kA/cm²) versus blue LDs fabricated on the semipolar(30-3-1) (dashed) orientation using the experimentally measured gain of19.3 cm⁻¹/(kA/cm²), where the back facet is coated for 99% reflectivityand the front facet is not coated to modify the reflectivity. Reasonablevalues of 200 kA/cm² and 90% were assumed for the transparency currentdensity and internal quantum efficiency, respectively. The simulationshows that the high gain semipolar device can achieve lasing with about3.5 kA/cm² threshold current density in a 150 μm long cavity or about 5kA/cm² in a 100 μm long cavity. The nonpolar device would require a 9kA/cm² threshold current density at a cavity length of 150 μm or about17 kA/cm² for a cavity length of 100 μm. A cavity length of 400 μm wouldbe needed to achieve about 3.5 kA/cm² for the nonpolar device. The lowthreshold current densities associated with short cavities laser diodeson semipolar proves the viability of such devices.

FIG. 6 presents the simulated threshold current density dependence onlaser cavity length for blue LDs fabricated on the nonpolar m-plane(solid) orientation using the experimentally measured differential modalgain of 6.6 cm⁻¹/(kA/cm²) versus blue LDs fabricated on the semipolar(30-3-1) (dashed) orientation using the experimentally measured gain of19.3 cm⁻¹/(kA/cm²), where the back facet is coated with 99% reflectivityand the front facet is coated for a about 75% reflectivity. Reasonablevalues of 200 kA/cm² and 90% were assumed for the transparency currentdensity and internal quantum efficiency, respectively. The simulationshows that the high gain semipolar device can achieve lasing with about3.5 kA/cm² threshold current density in a 50 μm long cavity and about 1kA/cm² in a 100 μm long cavity whereas the nonpolar device would require9 kA/cm² threshold current density at a cavity length of 50 μm. For thenonpolar device a cavity length of 200 μm would be needed to achieveabout 1 kA/cm².

In an example, the short cavity provides a highly efficient laser devicethat has higher dies/wafer. Additionally, the short cavity is ofteneasier to manufacture, and has a smaller form factor, which allows forintegration into a multitude of applications. Further benefits of thepresent device can be found throughout the present specification.

It was discovered that laser diodes fabricated on certain semipolarorientations of bulk gallium and nitrogen containing substrates such as(30-3-1), a (30-31), a (20-2-1), and a (20-21) can have novelproperties. Such semipolar planes can exhibit birefringence even whenthe laser cavities are aligned in the direction of highest gain, whichis in the projection of the c-direction. This birefringence leads to arotation of the polarization as the optical mode propagates along thecavity. For the family of semipolar planes with orientations that arerotated between the c-plane and the m-plane and the laser diode stripealigned in the projection of the c-direction, this result is somewhatunexpected since based on crystal symmetry alone there should be nobirefringence in these planes for cavities oriented along the projectionof the c-direction (Scheibenzuber et al., Physical Review B, 80, 115320,2009).

Certain embodiments provide methods to achieve high-performance,high-power laser diodes fabricated on semipolar orientations. Certainembodiments comprise an array of narrow laser diode cavities such thateach laser can only support a single lateral mode. In this multi-stripeembodiment, n laser stripes are defined under an electrode where all ofthe n laser stripes are operating in the single mode. For example, ifeach single lateral mode laser stripe can generate 100 mW of power anarray of n=10 stripes would form a 1 W laser device. In this example, ifeach single emitter width is 1.5 μm the total combined emitter widthwould be 15 μm, reducing the optical density at the facet by 10 timesand reducing the operating current density by 10 times, whilesimultaneously confining each stripe to the single mode for low internalloss. FIG. 7 shows a schematic image of a multi-stripe laser chipdepicting the cavity width and length including laser stripes 302 on anonpolar or semipolar GaN substrate 301. Each laser stripe ischaracterized by a cavity length L, a cavity width w, and front and backmirror facets. In certain embodiments, the multi-stripe laser shown inFIG. 7 makes use of multiple stripes supporting only single modes undera common electrode such that each stripe contribute to overall outputpower of the laser device and the total output area is increased whilemaintaining single mode operation in each stripe. FIG. 8 is a schematicdiagram of a cross-section of a multi-stripe laser configuration. Priorart exists on multi stripe laser arrays to prevent filamenting, reducethe thermal density, and for improved control over the far fieldpattern. However, deploying this technique to achieve larger totalemitter width and overcome increased loss associated with higher orderlateral modes enables one to leverage the desirable properties such ashigh gain from such semipolar orientations.

As shown in FIG. 8, the multiple cavity members 1002 are provided overthe substrate 1001. A layer of electrode 1003 is provided over thecavity member 1002 and the exposed region of the substrate 1001. Forexample, the electrode 1003 comprises p-type electrode. For example, adielectric layer 1004, which comprises substantially dielectricmaterial, is provided between the electrode 1003 and the substrate 1001.The substrate 1001 comprises an active region 1005. For example, theactive region 1005 comprises one or more quantum wells. In certainembodiments, the cavity member 1002 includes a via 1006. At the bottomside of the substrate 1001, the laser device comprises an electrode1007. For example, the electrode 1007 comprises an n-type contact. Invarious embodiments, the laser device is electrically coupled to a powersource through the electrodes 1003 and 1007.

It is to be appreciated that the shaped design as illustrated in FIG. 7and FIG. 8 can be used in various power settings. More specifically, thelaser device in FIG. 7 can operate with continuous wave output power ofgreater than 0.1 W, greater than 0.5 W, greater than 1 W, greater than 2W, greater than 5 W, greater than 10 W, or other power settings.Similarly, the operating voltage can be less than 7V, less than 6.5V,less than 6V, less than 5.5V, less than 5V, less than 4.5V, or othervoltages. As one of the benefit of the shaped design, the laser devicecan provide a peak wall plug efficiency of at least 15%, at least 20%,at least 25%, at least 30%, at least 35%, at least 40%, or even higher.Depending on the specific application, the spectral width can be greaterthan 0.3 nm, greater than 0.5 nm, greater 1 nm, greater than 2 nm,greater 3 nm, or other spectral width. As an example, spectral widthrefers to a range of frequencies or wavelengths emitted by a transmitterand surrounding the center frequency or wavelength at a power levelequal to half the maximum power level. Typically, relatively widespectral width (e.g., greater than 1 nm) is preferred in applicationssuch as pico projector systems.

A second example is for increased efficiency in very low optical outputpower applications of less than 25 mW where the conventional edgeemitting laser diode lengths of 450 μm to 600 μm are not optimal. Insuch low power applications high reflectivity coatings are often appliedto the front facet to reduce the mirror loss of the cavity and hencereduce the threshold current density such that the laser will achievethreshold at a lower current. This high reflectivity coating for reducedthreshold current has the undesired property of reducing the slopeefficiency of the laser diode such that the amount of unit opticaloutput power per unit of electrical input current is reduced. The resultis low optical output power for a given operating current. Short cavitylengths combined with the high gain of gallium and nitrogen containingsemipolar laser diodes breaks this trade-off by allowing for both lowthreshold current and high slope efficiency. The result is a highefficiency laser diode operating in this low power regime. With the highmodal gain characteristic of semipolar laser diodes and the appropriateselection of front facet mirror coating reflectivity, cavity lengths ofless than 50 μm, less than 100 μm, or less than 200 μm can be accessedwith viable threshold current density of less than 5 kA/cm² or less than3 kA/cm² with high slope efficiencies of greater than 0.6 W/A, greaterthan 0.9 W/A, greater than 1.2 W/A, or even greater than 1.5 W/A can beachieved.

A third benefit of this invention is the small form factor of the chipresulting from the short cavity. That is, by reducing the cavity lengthfrom the 500 μm to 600 μm range to the 50 μm to 100 μm range thefootprint of the chip can be reduced by 5- to 12-times. This can enablethe capability to pack a high density of individual laser diodes into asmall area or volume. Further, such tiny laser diodes can spawn theadoption of new ultra-compact package designs that are much smaller thanthe conventional TO56 or TO38 can-type packages. As a result, such tinypackaged laser diodes can be integrated into small objects previouslynot accessible such as pens/pencils, small key chains, cell phone cases,etc.

As used herein, the term GaN substrate is associated with GroupIII-nitride based materials including GaN, InGaN, AlGaN, or other GroupIII containing alloys or compositions that are used as startingmaterials. Such starting materials include polar GaN substrates (i.e.,substrate where the largest area surface is nominally an (h k l) planewherein h=k=0, and l is non-zero), non-polar GaN substrates (i.e.,substrate material where the largest area surface is oriented at anangle ranging from about 80 degrees to 100 degrees from the polarorientation described above towards an (h k l) plane wherein l=0, and atleast one of h and k is non-zero) or semipolar GaN substrates (i.e.,substrate material where the largest area surface is oriented at anangle ranging from about +0.1 degrees to 80 degrees or 110-179.9 degreesfrom the polar orientation described above towards an (h k l) planewherein l=0, and at least one of h and k is non-zero).

In an example, the present device can be enclosed in a suitable package.Such package can include those such as in TO-38 and TO-56 headers. Othersuitable package designs and methods can also exist, such as TO-9 orflat packs where fiber optic coupling is required and even non-standardpackaging. In a specific embodiment, the present device can beimplemented in a co-packaging configuration such as those described inU.S. Publication No. 2010/0302464, which is incorporated by referenceherein.

In other embodiments, the present laser device can be configured in avariety of applications. Such applications include laser displays,metrology, communications, health care and surgery, informationtechnology, and others. As an example, the present laser device can beprovided in a laser display such as those described in U.S. applicationSer. No. 12/789,303 filed on May 27, 2010, which is incorporated byreference herein.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. As an example, the packaged device can include any combination ofelements described above, as well as outside of the presentspecification.

As used herein, the term “substrate” can mean the bulk substrate or caninclude overlying growth structures such as a gallium and nitrogencontaining epitaxial region, or functional regions such as n-type GaN,combinations, and the like. For semipolar, the present method andstructure includes a stripe oriented perpendicular to the c-axis, anin-plane polarized mode is not an Eigen-mode of the waveguide. Thepolarization rotates to elliptic (if the crystal angle is not exactly 45degrees, in that special case the polarization would rotate but belinear, like in a half-wave plate). The polarization will of course notrotate toward the propagation direction, which has no interaction withthe Al band. The length of the a-axis stripe determines whichpolarization comes out at the next mirror. Although the embodimentsabove have been described in terms of a laser diode, the methods anddevice structures can also be applied to any light emitting diodedevice. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. A laser device comprising: a gallium and nitrogencontaining material having a semipolar surface configured on an offcutorientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51) plane, a (40-4-1) plane, (40-41) plane, a(30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a(30-3-2), or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to aprojection of a c-direction, the laser stripe region having a first endand a second end; a first facet provided on the first end of the laserstripe region; a second facet provided on the second end of the laserstripe region; an n-type cladding region overlying the semipolarsurface; an active region comprising at least one active layer overlyingthe semipolar surface, the active region comprising a quantum wellregion or a double hetero-structure region; and a p-type cladding regionoverlying the semipolar surface; wherein the laser stripe region ischaracterized by a width configured to emit a laser beam having aselected ratio of a first polarization state and a second polarizationstate, the width configured to emit the laser beam operable in a singlelateral mode with an internal loss of less than 9 cm⁻¹.
 2. The laserdevice of claim 1, wherein the laser device is configured to emitelectromagnetic radiation in a wavelength range selected from a 400 nmto 435 nm range, a 435 nm to 480 nm range, a 480 nm to 505 nm range, anda 505 nm to 550 nm range.
 3. The laser device of claim 1, wherein thefirst facet and the second facet are cleaved facets.
 4. The laser deviceof claim 1, wherein the first facet and the second facet are etchedfacets.
 5. The laser device of claim 1, wherein the laser beam isconfigured as a cross-polarized emission; wherein the first polarizationstate is a primary state and the second polarization state is asecondary state such that the power emitted in the second polarizationstate is at least 10% greater than, at least 20% greater than, at least30% greater than, or at least 40% greater than the power emitted in thefirst polarization state.
 6. The laser device of claim 1, wherein thelaser beam is configured to emit in a polarized state wherein the firstpolarization state is a primary state and the second polarization stateis a secondary state such that the power emitted in the secondpolarization state is at less than 10%, less than 5%, less than 1%, orless than 0.1% of the power emitted in the first polarization state. 7.The laser device of claim 1, wherein the laser device is configured fora pointer application, a display application, a medical application, abiological application, a manufacturing application, a projectorapplication, a visual application, a communication application, or ametrology application.
 8. The laser device of claim 1, wherein the laserstripe region is one of a plurality of laser stripes, wherein each ofthe plurality of laser stripes is configured in a parallel arrangementand is configured to emit in a polarized state wherein the firstpolarization state is a primary state and the second polarization stateis a secondary state such that the power emitted in the secondpolarization state is less than 10%, less than 5%, less than 1%, or lessthan 0.1% the power emitted in the first polarization state.
 9. Thelaser device of claim 1, wherein the offcut of the semipolar orientationis between +/−4 degrees toward a c-plane, between +/−10 degrees towardan a-plane, or between +/−4 degrees toward the c-plane and between +/−10degrees toward the a-plane.
 10. A laser device comprising: a gallium andnitrogen containing material having a semipolar surface configured on anoffcut orientation to one of either a (30-3-1) plane, a (30-31) plane, a(20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32) plane; anarray of N single lateral mode laser stripes formed overlying thesemipolar surface, wherein: each of the laser stripes is characterizedby a cavity orientation substantially parallel to a projection of ac-direction; each of the laser stripes is characterized by a widthranging from about 0.5 μm to about 2.5 μm; each of the laser stripes isconfigured to operate in a single lateral mode; each of the laserstripes is configured to emit a laser beam characterized by a firstpolarization state and a second polarization state, wherein the firstpolarization state is orthogonal to the second polarization state; andthe laser device is configured to emit a plurality of laser beams, eachof the plurality of laser beams characterized by a primary polarizationstate and a secondary polarization state, wherein a power emitted in thesecond polarization state is at less than 15% of a power emitted in thefirst polarization state, and the laser device is characterized by aninternal loss of less than 9 cm⁻¹ and a polarization ratio of at least90% or at least 95% between the power emitted in the first polarizationstate and the power emitted in the second polarization state.
 11. Thelaser device of claim 10, wherein the laser stripe region ischaracterized by a length greater than 20 μm and less than 500 μm, lessthan 200 μm, less than 100 μm, or less than 50 μm.
 12. The laser deviceof claim 10, wherein each of the laser stripe regions has a first endhaving a first facet and a second end having a second facet, and whereinthe first facet and the second facet are cleaved facets.
 13. The laserdevice of claim 10, wherein each of the laser stripe regions has a firstend having a first facet and a second end having a second facet whereinthe first facet and the second facet are etched facets.
 14. The laserdevice of claim 10, wherein the offcut of the semipolar orientation isbetween +/−5 degrees toward a c-plane, between +/−10 degrees toward ana-plane, or between +/−5 degrees toward the c-plane and between +/−10degrees toward the a-plane.
 15. The laser device of claim 10, whereinthe laser device is configured to emit in a polarized state wherein thepower emitted in the second polarization state is less than 10%, lessthan 5%, less than 1%, less than 0.1%, or less than 0.01%, the poweremitted in the first polarization state.
 16. The laser device of claim10, wherein the width ranges from 1.3 μm to 2 μm and is configured tomaintain a single lateral mode operation; and wherein N ranges from 2 to20.
 17. The laser device of claim 10, wherein each pair of laser stripesis laterally spaced by about 3 μm to about 200 μm; and furthercomprising a common p-type electrode region coupling the array of Nlaser stripes; and a common n-type electrode coupling the array of Nlaser stripes.
 18. The laser device of claim 10, further comprising anoptical coupling device to optically couple an emission from each of theN laser stripes to form a single emission.
 19. The laser device of claim10, wherein the laser device is configured for a pointer application, adisplay application, a medical application, a biological application, amanufacturing application, a projector application, a visualapplication, a communication application, or a metrology application.20. The laser device of claim 10, wherein the laser device is operableto emit electromagnetic radiation in a wavelength range selected from a400 nm to 435 nm range, a 435 nm to 480 nm range, a 480 nm to 505 nmrange, and a 505 nm to 550 nm range.
 21. The laser device of claim 10,wherein each of the laser stripe regions is configured to emit alinearly polarized laser beam, a circularly polarized laser beam, anelliptically polarized laser beam, or a combination of any of theforegoing.
 22. A laser device comprising: a gallium and nitrogencontaining material having a semipolar surface configured on an offcutorientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51), a (40-4-1) plane, a (40-41) plane, a (30-3-1)plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2)plane, or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to aprojection of a c-direction, the laser stripe region having a first endand a second end; a first facet provided on the first end of the laserstripe region; a second facet provided on the second end of the laserstripe region; an n-type cladding region overlying the semipolarsurface; an active region comprising at least one active layer regionoverlying the n-type cladding region; the active region comprising aquantum well region or a double hetero-structure region; and a p-typecladding region overlying the active region; a width characterizing thelaser stripe region configured to emit a laser beam having a firstpolarization state and a second polarization state, the firstpolarization state being orthogonal to the second polarization state andthe first polarization state being the primary polarization state, thewidth configured to emit the laser beam operable in a multi-lateral modewith an internal loss of less than 9 cm⁻¹; and a polarization ratio ofthe laser beam characterizing a cross-polarized emission such that atleast 1% of an emitted power is in the second polarization state. 23.The laser device of claim 22, wherein the first facet is a first etchedfacet and the second facet is a second etched facet.
 24. The laserdevice of claim 22, wherein the offcut of the semipolar orientation isbetween +/−5 degrees toward a c-plane, between +/−10 degrees towards ana-plane, or between +/−5 degrees toward the c-plane and between +/−10degrees towards the a-plane; wherein at least 20% of the emission is inthe second polarization state or wherein at least 30% of the emission isin the second polarization state or wherein at least 40% of the emissionis in the second polarization state.
 25. The laser device of claim 23,wherein the laser device is configured to emit electromagnetic radiationin a wavelength range selected from a 400 nm to 435 nm range, a 435 nmto 480 nm range, a 480 nm to 505 nm range, and a 505 nm to 550 nm range.26. The laser device of claim 23, wherein the laser device is configuredfor a pointer application, a display application, a medical application,a biological application, a manufacturing application, a projectorapplication, a visual application, a communication application, or ametrology application.
 27. A method of manufacturing an optical device,the method comprising: providing a gallium and nitrogen containingsemipolar member having a crystalline surface region; the semipolarsurface being configured on an offcut orientation to one of either a(60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a(40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a(20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane;the gallium and nitrogen containing member characterized by adislocation density of less than 10⁷ cm⁻²; forming a gallium andnitrogen containing n-type cladding layer overlying the surface region,the n-type cladding layer having a thickness from 300 nm to 6000 nm withan n-type doping level of 1E17 cm⁻³ to 6E18 cm⁻³; forming an n-sideseparate confining heterostructure (SCH) waveguiding layer overlying then-type cladding layer, the n-side SCH waveguide layer comprisinggallium, indium, and nitrogen with a molar fraction of InN of between 1%and 12% and having a thickness from 20 nm to 150 nm; forming an activeregion overlying the n-side SCH waveguiding layer, the active regioncomprising at least two quantum wells, the at least two quantum wellscomprising InGaN with a thickness of about 2 nm to about 8 nm; the atleast two quantum wells separated by barrier regions, the barrierregions comprising gallium and nitrogen with a thickness of about 2.5 nmto about 25 nm; forming a p-type gallium and nitrogen containingcladding layer overlying the active region, the p-type cladding layerhaving a thickness from 300 nm to 1000 nm with a p-type doping level of1E17 cm⁻³ to 5E19 cm⁻³; forming a p++ gallium and nitrogen containingcontact layer overlying the p-type cladding layer, the p++ gallium andnitrogen containing contact layer having a thickness from 10 nm to 120nm with a p-type doping level of 1E19 cm⁻³ to 1E22 cm³; and forming awaveguide member overlying the p++ gallium and nitrogen contact layer,the waveguide member aligned substantially in the projection of ac-direction, the waveguide member comprising a first end and a secondend, the first end having a first facet and the second end having asecond facet, the waveguide member being characterized by a widthconfigured to emit a laser beam having a selected ratio of a firstpolarization state and a second polarization state, the width configuredto emit the laser beam operable in a single lateral mode for an internalloss of less than 9 cm⁻¹.
 28. A laser device comprising: a gallium andnitrogen containing material having a semipolar surface configured on anoffcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51) plane, a (40-4-1) plane, (40-41) plane, a(30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a(30-3-2), or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to aprojection of a c-direction, the laser stripe region having a first endand a second end; a first etched facet provided on the first end of thelaser stripe region; a second etched facet provided on the second end ofthe laser stripe region; an n-type cladding region overlying thesemipolar surface; an active region comprising at least one active layeroverlying the semipolar surface, the active region comprising a quantumwell region or a double hetero-structure region; and a p-type claddingregion overlying the semipolar surface; wherein the laser stripe regionis characterized by a width configured to emit a laser beam having aselected ratio of a first polarization state and a second polarizationstate, the width configured to emit the laser beam operable in a singlelateral mode with an internal loss of less than 9 cm⁻¹.
 29. A laserdevice comprising: a gallium and nitrogen containing material having asemipolar surface configured on an offcut orientation to one of either a(60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51), a (40-4-1)plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1)plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane; a laserstripe region formed overlying a portion of the semipolar surface, thelaser stripe region being characterized by a cavity orientationsubstantially parallel to a projection of a c-direction, the laserstripe region having a first end and a second end; a first etched facetprovided on the first end of the laser stripe region; a second etchedfacet provided on the second end of the laser stripe region; an n-typecladding region overlying the semipolar surface; an active regioncomprising at least one active layer region overlying the n-typecladding region; the active region comprising a quantum well region or adouble hetero-structure region; and a p-type cladding region overlyingthe active region; a width characterizing the laser stripe regionconfigured to emit a laser beam having a first polarization state and asecond polarization state, the first polarization state being orthogonalto the second polarization state and the first polarization state beingthe primary polarization state, the width configured to emit the laserbeam operable in a multi-lateral mode with an internal loss of less than9 cm⁻¹; and a polarization ratio of the laser beam characterizing across-polarized emission such that at least 1% of an emitted power is inthe second polarization state.
 30. A method of using a laser device, themethod comprising: providing the laser device, the laser devicecomprising: a gallium and nitrogen containing material having asemipolar surface configured on an offcut orientation to one of either a(60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a(40-4-1) plane, (40-41) plane, a (30-3-1) plane, a (30-31) plane, a(20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32) plane; a laserstripe region formed overlying a portion of the semipolar surface, thelaser stripe region being characterized by a cavity orientationsubstantially parallel to a projection of a c-direction, the laserstripe region having a first end and a second end; a first facetprovided on the first end of the laser stripe region; a second facetprovided on the second end of the laser stripe region; an n-typecladding region overlying the semipolar surface; an active regioncomprising at least one active layer overlying the semipolar surface,the active region comprising a quantum well region or a doublehetero-structure region; and a p-type cladding region overlying thesemipolar surface; emitting a laser beam from the laser stripe region,wherein the laser stripe region is characterized by a width configuredto emit a laser beam having a selected ratio of a first polarizationstate and a second polarization state, the width configured to emit thelaser beam operable in a single lateral mode with an internal loss ofless than 9 cm⁻¹.
 31. A method of using a laser device, the methodcomprising: providing the laser device, the laser device comprising: agallium and nitrogen containing material having a semipolar surfaceconfigured on an offcut orientation to one of either a (30-3-1) plane, a(30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2), or a(30-32) plane; an array of N single lateral mode laser stripes formedoverlying the semipolar surface, wherein: each of the laser stripes ischaracterized by a cavity orientation substantially parallel to aprojection of a c-direction; each of the laser stripes is characterizedby a width ranging from about 0.5 μm to about 2.5 μm; each of the laserstripes is configured to operate in a single lateral mode; each of thelaser stripes is configured to emit a laser beam characterized by afirst polarization state and a second polarization state, wherein thefirst polarization state is orthogonal to the second polarization state;and emitting a plurality of laser beams from the laser device, each ofthe plurality of laser beams characterized by a primary polarizationstate and a secondary polarization state, wherein a power emitted in thesecond polarization state is at less than 15% of a power emitted in thefirst polarization state, and the laser device is characterized by aninternal loss of less than 9 cm⁻¹ and a polarization ratio of at least90% or at least 95% between the power emitted in the first polarizationstate and the power emitted in the second polarization state.
 32. Amethod of using a laser device, the method comprising: providing thelaser device, the laser device comprising: a gallium and nitrogencontaining material having a semipolar surface configured on an offcutorientation to one of either a (60-6-1) plane, a (60-61) plane, a(50-5-1) plane, a (50-51), a (40-4-1) plane, a (40-41) plane, a (30-3-1)plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2)plane, or a (30-32) plane; a laser stripe region formed overlying aportion of the semipolar surface, the laser stripe region beingcharacterized by a cavity orientation substantially parallel to aprojection of a c-direction, the laser stripe region having a first endand a second end; a first facet provided on the first end of the laserstripe region; a second facet provided on the second end of the laserstripe region; an n-type cladding region overlying the semipolarsurface; an active region comprising at least one active layer regionoverlying the n-type cladding region; the active region comprising aquantum well region or a double hetero-structure region; and a p-typecladding region overlying the active region; emitting a laser beam fromthe laser stripe region, a width characterizing the laser stripe region,the laser beam having a first polarization state and a secondpolarization state, the first polarization state being orthogonal to thesecond polarization state and the first polarization state being theprimary polarization state, the width configured to emit the laser beamoperable in a multi-lateral mode with an internal loss of less than 9cm⁻¹; and a polarization ratio of the laser beam characterizing across-polarized emission such that at least 1% of an emitted power is inthe second polarization state.
 33. A method of using a laser device, themethod comprising: providing the laser device, the laser devicecomprising: a gallium and nitrogen containing material having asemipolar surface configured on an offcut orientation to one of either a(60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a(40-4-1) plane, (40-41) plane, a (30-3-1) plane, a (30-31) plane, a(20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32) plane; a laserstripe region formed overlying a portion of the semipolar surface, thelaser stripe region being characterized by a cavity orientationsubstantially parallel to a projection of a c-direction, the laserstripe region having a first end and a second end; a first etched facetprovided on the first end of the laser stripe region; a second etchedfacet provided on the second end of the laser stripe region; an n-typecladding region overlying the semipolar surface; an active regioncomprising at least one active layer overlying the semipolar surface,the active region comprising a quantum well region or a doublehetero-structure region; and a p-type cladding region overlying thesemipolar surface; emitting a laser beam from the laser stripe region,wherein the laser stripe region is characterized by a width configuredto emit a laser beam having a selected ratio of a first polarizationstate and a second polarization state, the width configured to emit thelaser beam operable in a single lateral mode with an internal loss ofless than 9 cm⁻¹.
 34. A method of using a laser device, the methodcomprising: providing the laser device, the laser device comprising: agallium and nitrogen containing material having a semipolar surfaceconfigured on an offcut orientation to one of either a (60-6-1) plane, a(60-61) plane, a (50-5-1) plane, a (50-51), a (40-4-1) plane, a (40-41)plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21)plane, a (30-3-2) plane, or a (30-32) plane; a laser stripe regionformed overlying a portion of the semipolar surface, the laser striperegion being characterized by a cavity orientation substantiallyparallel to a projection of a c-direction, the laser stripe regionhaving a first end and a second end; a first etched facet provided onthe first end of the laser stripe region; a second etched facet providedon the second end of the laser stripe region; an n-type cladding regionoverlying the semipolar surface; an active region comprising at leastone active layer region overlying the n-type cladding region; the activeregion comprising a quantum well region or a double hetero-structureregion; and a p-type cladding region overlying the active region;emitting a laser beam from the laser stripe region, wherein the laserstripe region is characterized by a width configured to emit a laserbeam having a first polarization state and a second polarization state,the first polarization state being orthogonal to the second polarizationstate and the first polarization state being the primary polarizationstate, the width configured to emit the laser beam operable in amulti-lateral mode with an internal loss of less than 9 cm⁻¹; and apolarization ratio of the laser beam characterizing a cross-polarizedemission such that at least 1% of an emitted power is in the secondpolarization state.